Furniture extension mechanism

ABSTRACT

An article of furniture, such as a table, is convertible between a compact usable state and an extended usable state. A movable support surface (4) is extendable from a frame (21, 22). The movable support surface (4) has at least one leg (8) pivotally attached thereto, the leg (8) being ground engagable when the movable support surface (4) is in the extended state and the leg (8) being located out of sight under the frame (21, 22) and under the movable support surface (4) when the movable support surface (4) is in the compact state. Additional support surfaces may be (1) provided so as to be co-planar with the movable support surface (4) when the furniture is extended.

The present invention relates to extendible furniture such as tables,sofa beds and the like.

It is known to extend furniture such as tables by various means. Forexample, a table can be enlarged by the addition of an extra wing,either into the middle of the table or at one end thereof. Generallythis involves some means by which the frame of the table may beextended. Similarly, items of furniture such as sofa beds and chair bedsare known in which the interconversion from sofa to bed is achieved byextending the frame of the sofa.

United Kingdom Patent Specification No. 1 593 556 discloses aconvertible sofa bed having a converting mechanism which includes amovable carriage which is supported on a leg when the carriage isextended, which leg is retracted when the carriage is retracted. In themechanism of the prior-art, the supporting leg is stored in itsretracted position against the underside of the carriage and in front ofthe frame of the chair. This arrangement of the prior-art mechanismsuffers from the limitation that the height of the supporting leg isrelated to the distance from the front of the chair to the chair frame,which distance in turn is limited by the requirement for stability ofthe chair. Clearly, where the legs of the chair are part of the chairframe, then it is advantageous to position the frame as close aspracticable to the outer periphery of the load bearing part of the chairseat, in order to avoid the possibility of the chair toppling when saton, or in the case of such a mechanism being applied to a table, toavoid tipping over of the table should a user lean on its edge. However,positioning of the frame close to the edge of the chair, and inparticular to its forward edge, means that the supporting leg of theextended chair is of necessity short. Such an arrangement is thereforedisadvantageous for many designs of sofa bed or chair bed, and due totheir longer legs, is even more unsuitable for the extension of tables.

The object of the present invention is to seek to overcome the abovedisadvantages.

The present invention provides an article of furniture having at leastone support surface which is movable to allow the article assume eithera compact usable state or an extended usable state, characterised inthat the or each support surface has at least one leg pivotally attachedthereto, the pivotal leg being ground engagable when the article is inits extended state, the pivotal leg is stored under the movable supportsurface when the article is in its compact usable state, and means areprovided for moving the pivotal leg from its ground engaging mode to itsstorage mode on movement of the article from its extended state to itscompact state.

Preferably, when the article is in the compact usable state, the pivotalleg extends substantially parallel to the support surface.

Advantageously, the means for moving the pivotal leg from its groundengaging mode to its storage mode includes means for lifting the pivotalleg clear of the ground before the pivotal leg begins to pivot into thestorage state.

Conveniently, the lifting means comprises means for raising the supportsurface into a horizontal plane vertically higher than its plane whenthe article is in either the compact state or the extended state.

In a preferred embodiment, the lifting means comprises a connectionbetween the support surface and the article which permits limitedvertical flexible movement between them.

Advantageously, the means for moving the pivotal leg from its groundengaging mode to its storage mode includes a triple pivot arrangementcomprising first and second mutually pivotable elements the firstelement being additionally pivotally attached to the pivotal leg and thesecond element being additional pivotally attached to the supportsurface, biasing means for biasing the pivotal leg into the groundengaging mode and an abutment for initiating the pivotal movement of theelements and pivotal leg on engagement of an element against theabutment.

Conveniently, the pivotal leg is locked into its storage mode byengagement of the second element with the abutment.

The invention will now be described more particularly with reference tothe accompanying drawings, which show, by way of example only, twoembodiments of articles of furniture having an extension mechanismaccording to the invention.

IN THE DRAWINGS

FIG. 1 is a side view of a table with the additional table leaf in thestorage position;

FIG. 2 is a view similar to that of FIG. 1, but with the table extendedto bring the additional leaf into use;

FIG. 3 is a plan view from below of the table with the additional leafextended; and

FIG. 4 is a view similar to FIG. 2, but showing a section of a sofa-bedhaving an extension mechanism according to the invention, in theextended state.

Referring now to FIGS. 1 to 3, the extension mechanism and its use willnow be described.

When in its unextended position, the table comprises a tabletop 1, frameelements 21 and 22 and leg 3. The extra leaf 4 lies under the tabletop 1and has a frame element 5 attached thereto. The extra leaf 4 is extendedby pulling forwardly on the leaf 4 and/or frame element 5 so that theleaf 4 slides out from under the table top 1. The leaf 4 will continueto slide out until the bracket 6, which is attached to the leaf 4, comesinto juxtaposition with the leg 3, at which point stop 61 on bracket 6will engage with the leg 3, thus preventing any further forward movementof the leaf 4. As the leaf 4 slides from underneath it, the tabletop 1drops so that when the leaf 4 is fully extended, the leaf 4 and tabletop1 lie end to end, forming a flat surface.

The operation of the mechanism providing a leg as support for the leaf 4will now be described. As the leaf 4 is pulled out, its supporting legis simultaneously and automatically brought into position.

The supporting leg comprises a truncated channel section 7, a limb 8, achannel section 9, a rectangular member 10 and a hinge 11. The truncatedchannel section 7 is attached to the frame element 5 of the leaf 4 andis pivotally connected with the limb 8 by pivot pins 71. The limb 8,which is generally of U-shape in cross-section, is pivotally connectedat its upper end with one end of the channel section 9, by means ofpivot pins 81. The other end of channel section 9 is in turn pivotallyconnected with one end of the rectangular member 10, by means of pivotpins 91, while the opposite end of the member 10 is mounted on the hinge11, which is connected to the leaf 4. The limb 8 may optionally beprovided with a castor 82, as shown in FIG. 2.

In the unextended state, the supporting limb 8 lies generally parallelto and beneath the tabletop 1 and beneath the frame elements 21 and 22of the table. Since the limb 8 is positioned beneath frame element 22,it may extend beyond the element 22, allowing the limb 8 to be ofsuitable length so as to be able to contact the floor to support theleaf 4 when in the extended position. As the leaf 4 is extended, thelimb 8, falling under its own weight, begins to pivot downwardly aboutpivot pins 81. This action is assisted by spring 12 provided on thesection 7, which acts on limb 8. Simultaneously, as limb 8 falls, takingthe channel section 9 with it, channel section 9 and the rectangularmember 10 pivot with respect to one another about their pivot point andmember 10 swings downward on its hinge 11. When the limb 8 reaches itsresting point on the floor, the elements of the leg are biased into thisfinal position by the positioning of rectangular member 10 against theinner wall of channel section 9, effectively blocking any furtherpivoting in either direction.

The table may be readily and easily returned to the unextended positionas follows. Firstly, the tabletop 1 is lifted at its end juxtaposing theleaf 4 sufficient to allow the leaf 4 to be accommodated beneath it. Theleaf 4, together with its extended supporting limb 8 is then pushed inthe direction of the table leg 3. The limb remains extended until theframe element 22 comes into contact with the rectangular member 10. Asmember 10 hits frame element 22, its forward momentum first causesmember 10 to ride up element 22 a short distance, thereby lifting thelimb 8 just clear of the ground. At this point the further action of theframe element 22 on rectangular member 10 causes member 10 to pivot withrespect to channel section 9. This pivoting movement in turn causes thevarious elements to pivot in the directions of the arrows in FIG. 2,with the result that the limb 8 swings back up into its storageposition. The limb 8 is retained in the storage position by thepositioning of rectangular member 10 over the frame element 22 and underthe leaf 4.

Thus, in a table according to the invention, extension of the table canbe achieved by the one single manipulation of pulling out the extraleaf. The supporting leg for the leaf will automatically extend.Similarly, retraction of the supporting leg when closing the table isautomatic.

By varying the length of the member 10, the position of extension atwhich the pivotal limb 8 may begin to fall under its own weight may becontrolled. Thus, in cases where it is desired that the limb 8 shouldnot fall down until clear of, for example, a part of the fixed leg, theelement 10 may be correspondingly elongated. In reverse, this will alsoensure that the limb 8 will be retracted into its storage positionbefore it can come into contact with the fixed leg.

The mechanism described herein can be readily adapted to a sofa bed orchair bed as shown in FIG. 4. Since the supporting limb 8 folds neatlyunder the frame 22 when the sofa-bed or chair bed is in the compactstate, it will be appreciated that the appearance of the item as a pieceof living room furniture will be enhanced as the furniture's dualfunctionality will not be immediately obvious to an onlooker.

The spring 12, which assists in the release of the limb 8 duringextension of the furniture, may equally advantageously be positionedbetween channel section 9 and rectangular member 10, or between member10 and the leaf 4.

Various alternative embodiments of table having a mechanism of the typedescribed herein are to be considered to be within the scope of theinvention. For example, an extending mechanism including the pivotal legas described above may be provided on either side of the table, so thatthe surface of the table in its compact state comprises two leaves,joined for example by dowels, each leaf having its own extendingmechanism. Each leaf may be provided with a set of rails, one rail beingfixed to the table frame and the other rail being slidable in the fixedrail. When the leaves are separated, by extending one or both leaves, bysliding the leaf over its corresponding fixed rail, the space whichopens between them may be fitted with one or several additional leaves.In this way a table which is of a size to seat four people when in itscompact state, may readily be extended to seat upwards of sixteenpersons, depending on the number of additional leaves fitted. A supportsurface may be provided beneath the principle leaves, for storing theadditional leaves when not in use, this surface becoming accessible onseparation on the principle leaves.

The pivotal leg may be biased firmly into its ground engaging positionby arranging it such that when the furniture is extended, the leg is notvertical but angled so that the bottom of the pivotal leg ishorizontally further away from the fixed legs than is the top of thepivotal leg.

The elements of the mechanisms described may be composed of any suitablematerial, such as for example steel or wood.

What is claimed is:
 1. An article of furniture, comprising:a firstframe; at least one support surface which is movable relative to thefirst frame to allow the article to assume either a compact usable stateor an extended usable state; at least one leg pivotally attached to thesupport surface, the pivotal leg being ground engagable when the articleis in the extended usable state, and storable in a storage mode underthe movable support surface when the article is in the compact usablestate; and a frame member supported by the first frame for moving thepivotal leg from a ground engaging mode to the storage mode on movementof the article from the extended state to the compact state by firstlifting the pivotal leg clear of the ground before the pivotal legbegins to pivot into the storage state.
 2. An article of furniture asclaimed in claim 1, wherein when the article is in the compact usablestate, the pivotal leg extends substantially parallel to the supportsurface.
 3. An article of furniture as claimed in claims 1 or 2,wherein:the article further includes a triple pivot arrangement couplingthe pivotal leg to the support surface, the arrangement comprising firstand second mutually pivotable elements, the first element beingadditionally pivotally attached to the pivotal leg and the secondelement being additional pivotally attached to the support surface, andbiasing means for biasing the pivotal leg into the ground engaging mode;and the frame member comprises an abutment for initiating the pivotalmovement of the first and second elements and the pivotal leg uponengagement of the first and second elements against the abutment.
 4. Anarticle of furniture as claimed in claim 3, wherein the pivotal leg islocked into the storage mode by engagement of the second element withthe abutment.
 5. An article of furniture as claimed in claim 4, furthercomprising a connection between the support surface and the articlewhich permits limited vertical flexible movement between them.
 6. Anarticle of furniture as claimed in claims 4 or 5, wherein:the mechanismcomprises a triple pivot arrangement comprising first and secondmutually pivotable elements, the first element being additionallypivotally attached to the pivotal leg and the second element beingadditional pivotally attached to the support surface, and biasing meansfor biasing the pivotal leg into the ground engaging mode; and the framemember comprises an abutment for initiating the pivotal movement of thefirst and second elements and the pivotal leg upon engagement of thefirst and second elements against the abutment.
 7. An article offurniture as claimed in claim 6, wherein the pivotal leg is locked intothe storage mode by engagement of the second element with the abutment.